Bengt Klarin and colleagues at the University Hospital in Lund, Sweden, compared the probiotic treatment with chlorhexidine in 50 critically ill patients.

Microbiological testing revealed both treatments appeared to be equally effective at preventing potentially harmful bacteria from flourishing in the mouth and throat.

In addition, a probiotic that adheres to mouth lining will be able to work around the clock, unlike antiseptics which wear off after a few hours, say the authors.

The scientists said bigger studies were now needed to investigate the feasibility of using probiotics in this setting.

Bob Marsterton, chair of the British Society for Antimicrobial Chemotherapy's working party on hospital acquired pneumonia, said: "This is a plausible idea. But we need much larger trials that focus on clinical outcomes to prove it is an effective and affordable treatment."

He said chlorhexidine highly effective, affordable and readily available.

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